Kenta Sasaki

Synthesis of crystalline Si-based nanosheets by extraction of Ca from CaSi2 in inositol hexakisphosphate solution

Crystalline Si-based nanosheets were successfully synthesized from CaSi2 by a simple soft chemical synthetic method in solution. By immersing CaSi2 powder or CaSi2/Si substrates in an inositol hexakisphosphate (IP6) solution, Ca atoms were extracted from the CaSi2 particles, then Si-based nanosheets were formed. The morphological, structural and optical properties of the Si-based nanosheets were investigated. It is noted that the thin Si-based nanosheets stacked with a void space formed bundle structures, and the nanosheets were easily exfoliated from the bundles to expose the surfaces corresponding to the Si{111} planes. Meanwhile, the surface of the Si nanosheets might be terminated by O, H, or OH bonds. The Si-based nanosheet bundles were then formed and directly rooted to the Si(111) substrates, and had a remarkably highly symmetrical morphology. This study demonstrated a simple method for preparing Si-based nanosheets, and electro- and photo-chemical applications would possibly be expected, such as in lithium ion batteries.

Ripple compensation of suspension force and torque in a bearingless SPM motor with integrated winding

This paper describes a simple ripple compensation method of suspension force and torque in a bearingless surface-mounted permanent magnet (SPM) motor with two-phase integrated winding configuration. Only two H-bridges or eight power transistors are used for the proposed topology. The neutral point of each phase is connected to the middle point of the power sources to superimpose the suspension and toque producing currents into the two-phase integrated winding. The theoretical suspension force and torque for 8-slot/2-pole PM motor structure are derived. The finite element method analysis has been performed to verify the proposed ripple compensation method, and the results shows that the proposed method significantly decreases the suspension force and torque ripples.

Characteristic Modification of Catalysts by Use of a Chloride Source

Structural control and morphological modification of a series of Si-based nanostructures were studied from the viewpoint of modifying the catalyst’s characteristics. The catalyst was modified from a liquid to a solid during its growth. The growth evolution of the faceted Si nanowires occurred via a vapor–liquid–solid mechanism followed by a silicide vapor–solid–solid mechanism. The shapes of the catalysts defined the shapes of the nanowires during the vapor–solid–solid growth. The catalyst was further modified by the deposition of MnCl2. Only irregularly shaped Si particles or MnCl2 particles were observed on top of the Si nanowires. The characteristic modification of catalysts by liquid-phase crystal nucleation and deposition of liquid-phase droplets was discussed. In addition, the synthesis of a CrSi2 nanowire bundle by the formation of dense nanoparticles was studied.

Synthesis of Si-based Nanostructures by Extraction of Metallic Atoms from Silicides by Inositol Hexakisphosphate

Si-based nanostructures were synthesized by metallic atom extraction from silicides using inositol hexakisphosphate, which is known as a phytate for metal storage found in cereals and grains. The silicide bulk or powders were simply immersed in a diluted inositol hexakisphosphate solution, then dried. Si-based nanosheets and three dimensional network structure with SiOx were obtained. The structural property of the nanostructures was examined.